The invention relates to a process for the galvanoplastic production of substantially hollow jewelry made from metals, particularly precious metals with a least one mount for a stone, particularly a gem or semiprecious stone, in that the precious metal is electrolytically deposited on an electrically conductive mould core having the spatial contour of the piece of jewelry, after reaching the desired coating thickness the core is chemically or thermally dissolved and the core material removed through an opening in the precious metal coating.
Although the use of galvanoplastics or electroforming has long been known in the production of jewelry, particularly made from precious metals, the use of the process has hitherto been limited to exceptional cases, particularly the production of replicas of valuable originals or voluminous pieces of jewelry, in which a solid construction would lead to an excessive weight. However, it was disadvantageous in this connection that an electrolytic deposition from gold baths was only possible in the case of a relatively high fineness or carat level. However, of late baths and technologies have been developed enabling the deposition of finenesses starting from 8 carat. This has lead to a revival of this technology in the jewelry industry, so that nowadays jewelry of random shape and low carat values can be galvanoplastically produced. The coating thickness is a few hundred microns, so that attractive and at the same time lightweight pieces of jewelry can be produced which, despite their hollow construction, have an adequate dimensional stability.
In connection with the technology it is pointed out that the mould core is produced in conventional manner in a negative die of the piece of jewelry by slush moulding and it is possible to use all materials which can be thermally or chemically liquefied or volatilized, without attacking the metal. In the case of materials which are not in themselves electrically conductive, such as e.g. waxes, the mould core is electrically conductively coated with a metal and optionally the wax immediately removed, so that a hollow mould core is obtained. The dissolved core metal is removed through an opening in the precious metal coating formed during the deposition process or made subsequently.
In the case of jewelry items which are to be subsequently set with stones, particularly gems and which for this purpose must have corresponding amounts, it was not hitherto possible to use the galvanoplastic process or the galvanoplastically produced blank was separated in the vicinity of the mount and a conventionally cast solid part with a mount was soldered in. This process is naturally complicated and time-consuming and makes the piece of jewelry much more expensive.
In the case of conventional member mounts, the members are made from web or bar-like, solid sheet metal strips, which are conventionally soldered to the gem support and engage over the edges of the gem after pressing on. In the special case of the chaton mount, high, narrow webs are involved and engage round the edges of the gem in finger-like manner. Much the same applies with granular mounts, in which the gem is secured by individual small pin or column-like "granules", which project over the gem support and consequently also form a grazile mount with a greater incidence of light. In conventional processing the granules are obtained in that a type of chip is cut out from the solid mount material, bent up and subsequently shaped to form a head by mechanical working, the circumference of the gem being secured by several such granules. In certain cases the wall of the mount is subsequently worked out into the vicinity of the gem support, in order to obtain an even greater incidence of light. The gem support generally comprises solely a bearing or support ring, so that the back of the gem is also free for the incidence of light. Granular mounts include carreau, filamentary and pave mounts, which generally comprise sequenced or grid-like individual mounts. The frame or border mounts differ therefrom and generally engage in circular manner around the entire circumference of the gem and in general give a more solid impression.